Concerning a reactor vibration monitoring device that monitors vibrations of equipment in a nuclear reactor while the nuclear reactor is in operation, there has been known a technique of using ultrasonic waves to monitor vibrations of the internal equipment from the outside of reactor pressure vessel (for example, see Japanese Patent Application Laid-Open Publication Nos. 2009-068987 and 11-125688, the entire contents of which are incorporated here by reference).
Such a reactor vibration monitoring device will be described with reference to FIG. 16.
FIG. 16 is a block diagram showing a schematic configuration of a conventional nuclear reactor vibration monitoring device 107.
As shown in FIG. 16, the reactor vibration monitoring device 107 includes an ultrasonic transducer 103 which is installed on the outside surface of a reactor pressure vessel 100, transmits ultrasonic pulses to a reflector 102 attached to internal equipment 101 in the reactor pressure vessel 100, and receives reflected pulses.
The reflected pulses received by the ultrasonic transducer 103 are converted into a received signal through an ultrasonic receiver 104. The signal from the ultrasonic receiver 104 is received and processed by a signal processing unit 105. Vibration information processed by the signal processing unit 105 is displayed on a display unit 106.
In such a reactor vibration monitoring device 107, the reflector 102 is attached to the internal equipment 101 so that ultrasonic pulses transmitted from the ultrasonic transducer 103 are reflected by the reflector 102 and returned to the ultrasonic transducer 103. Consequently, even if the internal equipment 101 has a tilt and/or curvature, ultrasonic pulses can be transmitted and received with high sensitivity and reliability by a single ultrasonic transducer 103. Vibrations can be monitored based on changes in the time of signal received by the ultrasonic transducer 103.
In order for the reactor vibration monitoring device 107 to accurately monitor vibrations of the internal equipment 101 having a tilt and/or curvature, the reflector 102 needs to be attached to the internal equipment 101 so that ultrasonic waves are reflected with high efficiency. There has thus been a problem of attaching the reflector 102 in water by remote control.
The present invention has been achieved to solve the foregoing problem, and it is thus an object thereof to provide a reactor vibration monitoring device and monitoring method capable of accurately detecting vibrations of internal equipment having a tilt and/or curvature without attaching a reflector to the internal equipment in a reactor pressure vessel.